The present invention relates to a storage system and a storage controller.
For example, in a database system for treating a large amount of data such as a data center, etc., the data are managed by using a storage system constructed separately from a host computer. This storage system is constructed from e.g., a disk array device, etc. The disk array device is constructed by arranging many memory devices in an array shape, and is also constructed on the basis of e.g., RAID (Redundant Array of Independent Inexpensive Disks). At least one or more logical volumes (logical units) are formed in a physical memory area provided by a memory device group. This logical volume is provided to the host computer (more specifically, a database program operated in the host computer). The host computer can write and read data with respect to the logical volume by transmitting a predetermined command.
As the information society is advanced, etc., the data to be managed by the database are daily increased. Therefore, a storage controller of higher performance and larger capacity is required. The storage controller of a new type is developed to satisfy this market request. Two methods for introducing the storage controller of the new type into the storage system are considered. One of these methods is a method for perfectly replacing the storage controller of an old type and the storage controller of the new type and entirely constructing the storage system from the storage controller of the new type (JP-T-10-508967) (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application). The other method is a method for newly adding the storage controller of the new type to the storage system constructed by the storage controller of the old type and making the storage controllers of the new and old types coexist.
A technique for managing the memory area of a physical device in a sector unit and dynamically constructing the logical device in the sector unit is also known (JP-A-2001-337850).
Further, a technique for forming an area in conformity with the memory device of smallest capacity in the construction of the logical device from plural memory devices of different capacities, and forming areas in conformity with the smallest capacity with respect to the remaining capacities is also known (JP-A-9-288547).
When the storage controller is perfectly transferred from the storage controller of the old type to the storage controller of the new type, it is possible to utilize function and performance of the storage controller of the new type. However, no storage controller of the old type can be effectively utilized and introducing cost is increased. When it is intended that the storage controller of the old type and the storage controller of the new type coexist, the number of storage controllers constituting the storage system is increased and it takes much time and labor to manage and operate the storage controllers of both the new and old types.
Further, in a case in which responsibility of the memory device arranged in the storage controller of the old type is low, the performance of the entire system is reduced by connecting this memory device of the old type to the storage system. For example, this case is a case in which the memory device of the old type is a device involving a mechanical operation (head seek, etc.) and mechanical operation time is long and the capacity of a buffer for data transfer arranged in the memory device of the old type is small, etc.
Further, there is also a case in which no memory device of the old type can be utilized as it is as in the combination of an open system memory device and a main frame, or a server able to connect only the memory device having a specific function, etc.